Coronary sinus catheter

ABSTRACT

A catheter for insertion in the ostium of the coronary sinus in the right atrium comprised of a main reinforced portion, an intermediate zone portion and a soft tip portion, wherein a portion of the catheter is curved in a compound curve formed by a first and second curve, wherein the second curve may be curved in the same direction as the first curve or out of a plane formed by the first curve.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of Ser. No. 08/371,849 filedJan. 12, 1995 now U.S. Pat. No. 5,549,581 and Ser. No. 08/106,383 filedAug. 13, 1993 now U.S. Pat. No. 5,423,772.

BACKGROUND OF INVENTION

1. Field of Invention

This invention relates to cardiac catheters, more particularly, thisinvention relates to a specialized catheter to be used in the coronarysinus of the heart.

2. Prior Art

Catheters have been in use in medical procedures for many years. Forexample, they can be used to convey an electric stimulus to a selectedlocation within the human body. Further, they can be used to monitor andmake measurements for diagnostic tests of activities within the humanbody. Such catheters examine, diagnose and treat while positioned at aspecific location inside the human body which are otherwise inaccessiblewithout more invasive procedures. Recently, catheters have become morecommonly used within the human heart and vascular system. In such use,the catheter is first inserted into a major vein or artery which is nearthe body surface. The catheter is then guided to the area for diagnosisor treatment by manipulating the catheter through the vessels of thebody. As the utilization of catheters in remote and difficult to reachportions of the body including the heart has increased, it has becomeimportant to control precisely the movement of the catheter.

Control of the movement of catheters is difficult because of theinherent structure of the catheter. The body of conventional cathetersis long and tubular. To provide sufficient control over the movement ofthe catheter, it is necessary that its structure be somewhat rigid.However, the catheters must not be so rigid as to prevent navigation ofthe catheter through the body vessel to arrive at the precise locationwhere the medical procedure will be performed. In addition, it isimperative that the catheter not be so rigid as to cause damage to thebody vessel through which it is being passed.

While it is important that the catheter not be so rigid as to causeinjury to vessels and arteries, it is also important that there besufficient rigidity in the catheter to accommodate torque control, i.e.,the ability to transmit a twisting force along the length of thecatheter. Sufficient torque control enables controlled maneuverabilityof the catheter by the application of a twisting force at the proximalend of the catheter that is transmitted along the catheter to its distalend. The feature of existing catheters which provides greater torquecontrol often conflicts with the need for reduced rigidity to preventinjury.

One common method of addressing this problem has been the use ofcatheters with decreasing levels of rigidity through the length of thecatheter, particularly through the use of a "soft" tip at the distal endof the catheter. See, for example, U.S. Pat. Nos. 4,385,635, 4,886,506,5,122,125, 4,563,181, 4,863,442, 4,753,756, 4,636,346 4,898,591 and4,596,563.

As above stated, catheters are used increasingly for medical proceduresinvolving the human heart. In these procedures, the catheter being usedis typically guided to the heart through vessels including arteries,veins, and cardiac chambers and then it is placed at a precise locationwithin the heart. Typically, the catheter is inserted in an artery orvein in the leg, neck, upper chest or arm of the patient and threaded,often with the aid of a guidewire in the catheter, through variousarteries and veins until the tip of the catheter reaches the desiredlocation. The distal portion of the catheter may be preformed into adesired curvature so that by torquing the catheter about itslongitudinal axis, the catheter can be manipulated to the desiredlocation within the heart. For example, U.S. Pat. No. 4,882,777discloses a catheter with a complex curve at its distal end for specificprocedures in the right ventricle of a human heart. Further, U.S. Pat.No. 4,117,836 discloses a catheter for the selective coronaryarteriography of the left coronary artery and U.S. Pat. Nos. 5,016,640and 4,883,058 disclose catheters for the use in the right coronaryartery. In addition, U.S. Pat. No. 4,898,591 discloses a catheter withinner and outer layers containing braided portions. That patentdiscloses a number of different curvatures of intervascular catheters.

Unfortunately, none of the disclosed products are adequate for use inthe coronary sinus of the heart. The coronary sinus is the largestcardiac vein and runs along the atrioventricular groove and empties intothe right atrium. Thus, new catheters designed specifically for usewithin the coronary sinus are necessary.

Accordingly, it is an object of this invention to prepare a catheterdesigned for ease of access of, and for use in the coronary sinus.

Another object of this invention is to prepare a fixed shaped catheterfor use in the coronary sinus which can provide electrophysiologicalsensing for various locations within the coronary sinus.

It is a still further object of this invention to provide a fixed shapecoronary sinus catheter which can sense electrical activity in and/ordeliver electric energy to the right and left atria as well as the leftventricle.

These and other objects are obtained by the design of the coronary sinuscatheter of the instant invention.

SUMMARY OF INVENTION

The instant invention is a catheter for use in the coronary sinus of thehuman heart comprised of a main reinforced portion, an intermediate zoneportion and a softened tip portion, wherein the distal portion of thecatheter contains a double curve comprised of a first longitudinal curvewith a radius extending through an arc of about 30 to 50 degrees and asecond longitudinal curve with a radius extending through an arc ofabout 45 to about 90 degrees. In one preferred embodiment both the firstand second longitudinal curves are curved in the same direction and aregenerally coplanar. See FIGS. 2 and 3. In a second preferred embodiment,the second curve curves out of plane of the first curve from about 15 toabout 90 degrees. See FIGS. 4A, 4B and 4C.

While the instant catheter is designed for use in the coronary sinus, itis certainly not limited to that application but can be used for otherprocedures in the heart and in other locations within the body. Further,the catheter's use is certainly not limited to electrophysiologicaldiagnostic applications but can be used for interventional pacing,defibrillation, ablation, cardioversion and other such cardiacprocedures.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cut away view of the human heart, specifically the rightatrium, illustrating the relative location, for example, of the inferiorvena cava, fossa ovalis, superior vena cava, valve of the coronary sinusand the ostium of the coronary sinus.

FIG. 2 is a side perspective view of the first preferred embodiment ofthe catheter 2.

FIG. 3 is a front view of the first preferred embodiment of the catheter2.

FIG. 4A is a side perspective view of the second preferred embodiment ofthe catheter 2 with a portion 12 of the distal end of the catheter outof plane with the remainder of the catheter, wherein a stop cock 14 anda side port tubing 16 attached to the proximal end of the catheter aredirected to the right of the catheter.

FIG. 4B is a front view of the catheter 2 of FIG. 4A rotated 90°counterclockwise when viewed from the perspective of the proximal end ofFIG. 4A such that the stop cock 14 is directed in front of the catheter2.

FIG. 4C is a top view of the catheter of FIG. 4A rotated upward 90° fromits position in FIG. 4A such that the stop cock 14 is also directed tothe right of the catheter 2.

DETAILED DESCRIPTION OF THE DRAWINGS

A coronary sinus catheter 2 in accordance with this invention isprovided for maintaining precise location and continuous electricalcontact within the coronary sinus of the heart.

Increasingly, procedures have been designed to investigate, analyze anddiagnose the cause of arrhythmias that occur in the heart. In a normalheart contraction and relaxation of the heart muscle takes place aselectrochemical signals pass sequentially through the myocardium fromthe atria to the ventricular tissue along a well defined route includingthe His-Purkinje System. The signal originates at a site called thesinus node in the right atrium. Methods to diagnose the cause of certainarrhythmias include connection of a patient to patch leads placed on thechest of the patient to record the electrical activity of the heart.These procedures are commonly called electrocardiograms. The record ofelectrical activity as a function of time is referred to as an"electrogram." However, more specific information with regard to thepatient's arrhythmia can be gained by placing diagnosticelectrophysiology catheters with sensing electrodes at specificlocations in the heart. Once these electrodes are in a predetermined,precise location within the heart, readings can be taken which will helpdetermine the types of arrhythmias and diagnose the problems of thepatient's heart. These electrophysiological analysis require the preciseplacement of the electrophysiological catheter within the heart.Examples of locations for the placement of these catheters includedesignated points within the right atrium, the right ventricle, near thebundle of the His and, especially when information is desired from theleft side of the heart, in the coronary sinus.

The coronary sinus is the largest cardiac vein which serves as a venousconduit from smaller veins within the myocardium to the right atrium.The coronary sinus extends from an opening for the coronary sinus in theright atrium, along the posterior of the heart to the left side of theheart along the atrioventricular border. When an electrophysiologycatheter is placed in the coronary sinus, intracardiac electrograms maybe obtained from the left atrium as well as the left ventricle if propercontact is made with the designated locations in the heart. In addition,if electrodes are placed on the catheter outside of the coronary sinus,electrograms may be obtained of activity within the right atrium andeven from the right ventricle. The location of the electrodes and theirsize, shape and location on the catheter may vary depending on the needsof the physician and the specific procedures for which the catheter isutilized. Preferably, the electrodes are located from the tip of thecatheter up to 20.0 cm., or more proximally, from the tip along the bodyof the catheter.

To understand the use of such a catheter, it is first important toreview the structure of the human heart as shown in FIG. 1. A typicalhuman heart contains four chambers, a right and left atrium and rightand left ventricle. The right atrium of the heart receives bloodreturning to the heart through the inferior vena cava and superior venacava. Adjacent to the opening in the right atrium of the inferior venacava is the ostium of the coronary sinus. A tissue fold or primitivevalve covers the coronary sinus ostium to prevent blood from backflowinginto the coronary sinus as it is being pumped out of the right atrium.(Gray, Anatomy of the Human Body, 23rd. Ed. p. 527 (1936)) This coronarysinus ostium is a compliant semi-circular fold comprised of the liningmembrane of the atrium. Within the right atrium generally and above thecoronary sinus valve specifically is an oval depression called the fossaovalis. Between the inferior vena cava and the coronary sinus ostium isthe eustachian ridge. The precise location of each of these elements mayvary from patient to patient.

One of the difficulties in performing procedures within the coronarysinus is finding the ostium to the coronary sinus while the heart isbeating. As earlier stated, the opening or ostium of the coronary sinusis located in the right atrium between the tricuspid valve, the fossaovalis and the inferior vena cava. Two approaches have been used for theplacement of an electrophysiology catheter within the coronary sinus, aninferior approach from below the heart and a superior approach fromabove the heart. In the inferior approach a catheter is advanced throughthe femoral vein into the right atrium. The tip of the catheter is thencurved remotely to aim it toward the ostium of the coronary sinus. Inthe superior approach, a catheter is advanced through either theinternal jugular or subclavian vein through the superior vena cava intothe right atrium until it is directed toward the coronary sinus.

Gaining access to the ostium of the coronary sinus is a very difficultprocedure. As previously discussed, there are a number of anatomicalstructures within the right atrium which can be easily confused with thecoronary sinus. Further, these particular features of the heart do notshow up well on a fluoroscope, thus making the procedure quite difficultand time consuming for the physician.

The catheter 2 of the present invention is specifically configured toavoid these problems by its insertion into the right atrium to aposition adjacent to the coronary sinus ostium. The catheter of theinstant invention has a preformed curvature which permits it to beeasily manipulated into the coronary sinus. In addition, the specificnature of the curve of the instant catheter permits importantelectrophysiological readings to occur while the catheter is within thecoronary sinus, including analysis of both the right and left atrium andthe left ventricle.

As shown in FIGS. 2 and 3, in one preferred embodiment the catheter ofthe present invention has a distal end and a proximal end. It generallyhas three portions, a main reinforced portion (Section 3), anintermediate zone portion (Section 2) and a softened tip portion(Section 1). The intermediate zone portion is more pliable than the mainreinforced portion and the softened tip portion is more pliable than theintermediate zone portion. This increase in pliability can be achievedthrough conventional procedures well known in the industry. For example,the main reinforced portion can be formed of any conventional materialhaving "memory" or permitting distortion from, and subsequentsubstantial return to, the desired shape. To reinforce this mainreinforced portion, a reinforcing braid or other such suitable strandmaterial having high tensile strength may be wound around the length ofthe main reinforced portion or incorporated into that portion of thecatheter. Suitable reinforcing braid may be prepared from materials suchas stainless steel, aramids sold under the trademark Kevlar by E. I.DuPont and nickel chromium alloys.

The intermediate zone portion is preferably formed of the same or asimilar material with similar performance characteristics as is thereinforced zone portion but without addition of the reinforcing braid.The location of the merger of the reinforced section with theintermediate zone portion is not particularly critical. In a preferredembodiment, this junction is from about 7.0 to about 13.0 cm. andpreferably from about 9.0 to about 11.0 cm. from the distal tip of thecatheter. Distal from the intermediate zone is the softened tip portionwhich is more pliable than either the main reinforced portion or theintermediate zone portion. This enhanced pliability can be achieved by anumber of methods well known in the industry and including use of afused flexible tip catheters and soft tip catheters comprised of thesame or similar materials with similar performance characteristics asare the reinforced and intermediate zone portions. Such tip designs aredisclosed in U.S. Pat. Nos. 5,088,991, 4,596,563 and 5,078,702. Inaddition, a softened tip can be created through modifications made inthe catheter such as additional drawing of the catheter body to reducethe thickness of the walls, thus achieving the enhanced pliability.

The relative length of the three zones are approximately 10.0 to about130.0 cm. in length for the reinforced zone, about 5.0 to about 8.0 cm.in length for the intermediate zone and about 2.0 cm. to about 4.0 cm.in length for the softened tip portion. As will be discussed in moredetail, although a preferred embodiment utilizes three zones of thecatheter with varying degrees of rigidity, zones of the catheter withvarying rigidity may be present. The essential element is the particularshape chosen for the catheter.

The curvature of the instant catheter contains two curves. After theextended straight portion of the catheter contained in the reinforcedportion and a portion of the intermediate portion, the curvature beginswithin the intermediate zone of the catheter. This first preformedcurvature is a longitudinal curve with a radius from about 7.0 cm. toabout 11.0 cm., preferably from 8.0 cm. to 10.00 cm. and most preferablyabout 9.0 cm. in length. This first curvature curves through an arc ofabout 30 to about 50 degrees, preferably from about 35 to about 45degrees and most preferably about 40 degrees of arc. At the distal endof this first curve is a second longitudinal curve or "hook curve" witha radius from about 0.5 to about 2.0 cm., preferably from about 0.5 toabout 1.5 cm. and most preferably about 1.0 cm. The second curve extendsthrough an arc from about 45 to about 90 degrees, preferably from about50 to about 70 degrees and most preferably about 60 degrees of arc. Thesecond curve is an extension of the first curve, which may curve in thesame direction as the first curve. This second "hook curve" serves topartially limit the depth to which the distal end of the catheter can beinserted into the coronary sinus. In one preferred embodiment, the firstand second longitudinal curves are substantially coplanar (within about15 degrees of coplanar), though minor variations in the curve outside ofthe plane of the catheter are certainly within the confines of theinvention. This second "hook curve" serves to partially limit the depthto which the distal end of the catheter can be inserted into thecoronary sinus.

In a second preferred embodiment, the second longitudinal curve curvesout-of-plane of the first longitudinal curve from about 15 to about 90degrees and preferably from about 30 to about 75 degrees out-of-plane.See FIGS. 4A, 4B and 4C. This alternative preferred embodiment isdesigned for use when the inferior approach is used for introduction ofthe catheter into the coronary sinus. The out-of-plane curve 12 of the"hook curve" permits easier approach than with the first preferredembodiment of the coronary sinus catheter.

For the purpose of illustration and not limitation, the diameter of thecatheter may vary from about 3.0 to about 8.0 "French" units (one"French" equals about one-third of a millimeter).

Toward the distal end of the catheter within a portion of the mainreinforced portion, the intermediate zone portion and the softened tipportion may be placed a plurality of electrodes 20, preferably at leasttwo with one of those at the tip. See FIGS. 4A-4C. The number ofelectrodes and their placement on the body of the catheter will dependon the intended usage for the catheter. The ultimate number ofelectrodes may be as many as 10 or more electrodes. In one preferredembodiment, an electrode is placed both at the tip of the catheter andapproximately where the first and second curves meet. By this placement,when the catheter of the instant invention is placed within the coronarysinus for sensing purposes, the catheter will be able to sense bothsides of the coronary sinus at the same time.

The catheter of the instant invention preferably is divided into threeportions: a main reinforced portion, Section 3, an intermediate zoneportion, Section 2, and a softened tip portion, Section 1. See FIGS. 2and 3. However, catheters for a number of uses with the specificcurvature but without the three distinct portions of the instantinvention are also covered by this disclosure. The relative rigidity ofthe catheter throughout its length may not be particularly important aslong as the desired curvature is present. Alternatively, the intendeduse for the catheter may be best accomplished by only two portionshaving different rigidity along the length of the catheter body. Morefrequent modifications of the rigidity of the catheter body than threemay also be necessary, depending on the required use of the catheter.

If appropriate to the intended use, a lumen may also be incorporatedinto the catheter for infusion of fluids or withdrawal of blood samples.The diameter of the lumen should be sufficient to accomplish theintended use for the catheter. In this embodiment one or a plurality ofvents 18 would also be located near the distal tip of the catheter withthe precise location and number depending on the intended use for thecatheter. See FIGS. 4A-4C.

In operation, a coronary sinus catheter as described in the instantinvention containing electrodes from 2 to about 10 connected toelectrophysiology sensing devices in one embodiment is insertedpercutaneously through the internal jugular vein or the subclavian veinand advanced under fluoroscopic control through the superior vena cavato the right atrium. Insertion is also possible in the second preferredembodiment using the brachial vein or femoral vein approach. Thecoronary sinus catheter is then directed across the right atrium untilit contacts the ostium of the coronary sinus. The particular structureand curvature of the instant coronary sinus catheter permits ease inlocating the ostium of the coronary sinus. Under fluoroscopic guidancethe catheter is advanced towards the tricuspid valve with the tippointed medially. The tip of the coronary sinus catheter is theninserted within the coronary sinus and advanced as far as is required ordesired. Continuous and stable recordings of the electrical pathwaysrunning near the coronary sinus can then be produced. As a result of theunique curvature of the coronary sinus catheter, as well as the uniquestructure of that catheter, it is relatively easy to locate the ostiumof the coronary sinus and, in addition, take electrophysiology readingswithin the coronary sinus. In this fashion the time and x-ray exposurerequired during the procedure can be reduced.

In addition to the use for the coronary sinus catheter as a diagnosticelectrophysiology catheter, it may also be used for other medicalprocedures within the coronary sinus. For example, by modifying the modeof the use for the electrodes of the catheter, the types of medicalinstruments to which the proximal end of the catheter is attached, andthe electrodes, the catheter can also serve as a means forinterventional pacing or permanent pacing of the heart. Pacing using thecoronary sinus catheter will also provide the ability to pace the leftatrium. By the administration of a controlled amount of electricalenergy to the heart, which is at that time experiencing an arrhythmia,the coronary sinus catheter may also be used for defibrillation purposesor for cardioversion. The catheter may also be utilized for permanentimplantable pacing by various modifications to the catheter. For thisapplication the material used to manufacture the catheter may bemodified to better adapt to long-term invasive medical procedures. Forexample, when the catheter functions as a permanent pacing catheterlead, the structure of the catheter may not contain braided portionswhich might interfere with the pacing procedures. Further, the shape,size and placement of the electrodes on the catheter may also bemodified for the specialized procedure. Other uses well known in theindustry are also contained within the description of the invention.

While it is apparent from the foregoing that particular forms of theinvention have been illustrated and described, various modifications canbe made without departing from the spirit and scope of the invention.Accordingly, it is not intended that the invention be limited except bythe appended claims.

We claim:
 1. A catheter for use in the coronary sinus comprising anelongated member comprising a generally straight, proximal section, anda curved distal section, wherein the distal section comprises a firstand second curve, wherein the first curve is curved through an overallarc of about 30 to about 50 degrees, wherein the second curve is curvedthrough an overall arc of about 50 to about 70 degrees, and wherein thesecond curve is curved out of a plane formed by the first curve in anoverall angle from about 30 to about 90 degrees.
 2. A catheter for usein the coronary sinus comprising an elongated member comprising a mainreinforced portion, an intermediate zone portion and a tip portion,wherein the intermediate zone portion is constructed of conventionalcatheter material, wherein the tip portion is constructed more pliablethan the intermediate zone portion, wherein the elongated membercomprises a generally straight, proximal section and a curved distalsection, wherein the distal section comprises a first and second curve,wherein the first curve is curved through an overall arc of about 30 toabout 50 degrees, wherein the second curve is curved through an overallarc of about 50 to about 70 degrees, and wherein the second curve iscurved out of a plane formed by the first curve in an overall angle fromabout 30 to about 90 degrees.
 3. The catheter of claim 1 wherein thesecond curve is curved out of the plane formed by the first curve fromabout 30 to about 75 degrees.
 4. The catheter of claim 3 wherein thesecond curve is curved out of the plane formed by the first curve fromabout 30 to about 75 degrees.